DEV: Rename direct message related models

This is a followup of the previous refactor where we created two new
models to handle all the dedicated logic that was present in the
`ChatChannel` model.

For the sake of consistency, `DMChannel` has been renamed to
`DirectMessageChannel` and the previous `DirectMessageChannel` model is
now named `DirectMessage`. This should help reasoning about direct
messages.

plugins/chat/lib/chat_channel_fetcher.rb

@@ -53,7 +53,7 @@ module Chat::ChatChannelFetcher
         .select(:id)
         .joins(
           "INNER JOIN direct_message_channels ON direct_message_channels.id = chat_channels.chatable_id
-            AND chat_channels.chatable_type = 'DirectMessageChannel'
+            AND chat_channels.chatable_type = 'DirectMessage'
         INNER JOIN direct_message_users ON direct_message_users.direct_message_channel_id = direct_message_channels.id",
         )
         .where("direct_message_users.user_id = :user_id", user_id: guardian.user.id)
@@ -134,7 +134,7 @@ module Chat::ChatChannelFetcher
       query
         .joins(:user_chat_channel_memberships)
         .where(user_chat_channel_memberships: { user_id: user_id, following: true })
-        .where(chatable_type: "DirectMessageChannel")
+        .where(chatable_type: "DirectMessage")
         .where("chat_channels.id IN (#{generate_allowed_channel_ids_sql(guardian)})")
         .order(last_message_sent_at: :desc)
         .to_a

plugins/chat/lib/chat_mailer.rb

@@ -50,7 +50,7 @@ class Chat::ChatMailer
         (uccm.last_unread_mention_when_emailed_id IS NULL OR c_msg.id > uccm.last_unread_mention_when_emailed_id) AND
         (
           (uccm.user_id = c_mentions.user_id AND uccm.following IS true AND cc.chatable_type = 'Category') OR
-          (cc.chatable_type = 'DirectMessageChannel')
+          (cc.chatable_type = 'DirectMessage')
         )
       SQL
       .group("users.id, uccm.user_id")

plugins/chat/lib/direct_message_channel_creator.rb

@@ -7,13 +7,13 @@ module Chat::DirectMessageChannelCreator
   def self.create!(acting_user:, target_users:)
     Guardian.new(acting_user).ensure_can_create_direct_message!
     target_users.uniq!
-    direct_messages_channel = DirectMessageChannel.for_user_ids(target_users.map(&:id))
-    if direct_messages_channel
-      chat_channel = ChatChannel.find_by!(chatable: direct_messages_channel)
+    direct_message = DirectMessage.for_user_ids(target_users.map(&:id))
+    if direct_message
+      chat_channel = ChatChannel.find_by!(chatable: direct_message)
     else
       ensure_actor_can_communicate!(acting_user, target_users)
-      direct_messages_channel = DirectMessageChannel.create!(user_ids: target_users.map(&:id))
-      chat_channel = direct_messages_channel.create_chat_channel!
+      direct_message = DirectMessage.create!(user_ids: target_users.map(&:id))
+      chat_channel = direct_message.create_chat_channel!
     end
 
     update_memberships(acting_user, target_users, chat_channel.id)

plugins/chat/lib/discourse_dev/direct_channel.rb

@@ -6,7 +6,7 @@ require "faker"
 module DiscourseDev
   class DirectChannel < Record
     def initialize
-      super(::DirectMessageChannel, 5)
+      super(::DirectMessage, 5)
     end
 
     def data

plugins/chat/lib/discourse_dev/message.rb

@@ -11,7 +11,7 @@ module DiscourseDev
 
     def data
       if Faker::Boolean.boolean(true_ratio: 0.5)
-        channel = ::ChatChannel.where(chatable_type: "DirectMessageChannel").order("RANDOM()").first
+        channel = ::ChatChannel.where(chatable_type: "DirectMessage").order("RANDOM()").first
         channel.user_chat_channel_memberships.update_all(following: true)
         user = channel.chatable.users.order("RANDOM()").first
       else

plugins/chat/lib/extensions/user_notifications_extension.rb

@@ -20,7 +20,7 @@ module Chat::UserNotificationsExtension
           (uccm.last_unread_mention_when_emailed_id IS NULL OR chat_messages.id > uccm.last_unread_mention_when_emailed_id) AND
           (
             (cm.user_id = :user_id AND uccm.following IS true AND chat_channels.chatable_type = 'Category') OR
-            (chat_channels.chatable_type = 'DirectMessageChannel')
+            (chat_channels.chatable_type = 'DirectMessage')
           )
         SQL
         .to_a

plugins/chat/lib/guardian_extensions.rb

@@ -153,10 +153,10 @@ module Chat::GuardianExtensions
     return false if !can_modify_channel_message?(message.chat_channel)
 
     if message.user_id == current_user.id
-      case chatable.class.name
-      when "Category"
+      case chatable
+      when Category
         return can_see_category?(chatable)
-      when "DirectMessageChannel"
+      when DirectMessage
         return true
       end
     end